The Proxy Mobile Internet Protocol version 6 (PMIPv6) provides a network-based mobility management protocol. An MN does not need to participate in any mobility management signaling on a PMIPv6 network. A mobility entity on the network traces mobility of the MN, initializes mobility signaling, and sets up routing information required for communication.
FIG. 1 shows the structure of a PMIPv6 network system in the prior art. As shown in FIG. 1, the network system includes a local mobility anchor (LMA), a MAG, and an MN. The LMA on the PMIPv6 network maintains the reachability state of the MN and acts as an anchor of a home network prefix (HNP) of the MN on the topology. The MAG is an entity that represents the MN to implement mobility management. The MAG detects mobility of the MN on an access link and sends a proxy binding update (PBU) message to the LMA corresponding to the MN. When the MN accesses the PMIPv6 network, the MAG on the access link determines, after identifying the MN and obtaining its ID, whether the MN is authorized with the network mobility management service. If the system needs to provide the network mobility management service for the MN, it ensures that the MN can use any address configuration mechanism allowed by the network so that the MN obtains the address configuration on an interface and moves anywhere on the PMIPv6 network. The address configuration obtained by the MN includes the address of the HNP, address of the default router on the link, and configuration of related parameters. From the perspective of the MN, the entire PMIPv6 network can be regarded as a single link. The system ensures that the address obtained by the MN does not change and always considers that the MN is on a same link. If the MN is connected to the PMIPv6 network through multiple interfaces, the LMA allocates a unique HNP to each interface so that each interface configures its home address (HoA) according to its HNP. If the MN hands over from one interface to another interface on a same PMIPv6 network, the LMA allocates a same HNP to the new interface. As a topological anchor of the MN, the LMA receives any encapsulated packets sent to the MN. After receiving an encapsulated packet whose destination address prefix is the HNP of the MN, the LMA forwards the encapsulated packet to the MAG through a tunnel. After receiving the encapsulated packet, the MAG decapsulates it and sends the decapsulated packet to the MN. As the default gateway of the MN, after receiving any encapsulated packet sent to a correspondent node (CN), the MAG forwards the encapsulated packet to the LMA through a tunnel. After receiving the encapsulated packet, the LMA decapsulates it and sends the decapsulated packet to the destination CN.
When the access link of the MN changes, a MAG on a new access link sends signaling to the LMA to update binding information on the LMA. The MAG on the new link sends a router advertisement (RA) message carrying a corresponding HNP to the MN, so that the MN believes that it is still on the same link. In addition, the MN uses the same address configuration on the new access link. Therefore, the MAG needs to notify the LMA of a handover state of the MN through a PBU message, so that the LMA performs a corresponding operation according to the handover state of the MN. In the prior art, the method for a MAG to obtain a handover state of an MN includes that: a new MAG may obtain the handover state of the MN from an old MAG through context transmission between the MAGs; or the new MAG uses an Authentication, Authorization and Accounting (AAA) architecture to obtain the handover state of the MN from the AAA server.